1. Overview

The exec module allows external commands to be executed from a Kamailio
script. The commands may be any valid shell commands--the command string is
passed to the shell using “popen” command. Kamailio passes
additional information about the request in environment variables:

SIP_HF_<hf_name> contains value of each header field in
request. If a header field occurred multiple times, values are
concatenated and comma-separated. <hf_name> is in capital
letters. Ff a header-field name occurred in compact form,
<hf_name> is canonical.

SIP_TID is transaction identifier. All request retransmissions or
CANCELs/ACKs associated with a previous INVITE result in the same
value.

SIP_DID is dialog identifier, which is the same as to-tag.
Initially, it is empty.

SIP_SRCIP is source IP address from which request came.

SIP_ORURI is the original request URI.

SIP_RURI is current request URI (if
unchanged, equal to original).

SIP_USER is userpart of current request URI.

SIP_OUSER is userpart of original request URI.

NOTE: The environment variables must be specified with double $
(e.g., $$SIP_OUSER) in the parameters given to exec functions.
Otherwise they will be evaluated as Kamailio pseudo-variables,
throwing errors.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

No dependencies on other Kamailio modules.

2.2. External Libraries or Applications

The following libraries or applications must be installed before running
Kamailio with this module loaded:

None.

3. Parameters

3.1. setvars (integer)

Turn off to disable setting environment variables for executed commands.

Default value is 1.

Example 1.1. Set “setvars” parameter

...
modparam("exec", "setvars", 1)
...

3.2.
time_to_kill (integer)

Specifies the longest time a program is allowed to execute. If the
time is exceeded, the program is killed.

Default value is 0.

Example 1.2. Set “time_to_kill” parameter

...
modparam("exec", "time_to_kill", 20)
...

4. Functions

4.1.
exec_dset(command)

Executes an external command. Current URI is passed to the command
as parameter. Output of the command is considered URI set
(separated by lines).

Meaning of the parameters is as follows:

command - Command to be executed. It can
include pseudo- variabes;

WARNING: if the var you are passing out has a bash special
character in it, the var needs to be placed inside quotes, for example:
exec_dset("print-contact.sh '$ct'");

4.3.
exec_avp(command [, avplist])

Executes an external command. Each line from output of the command
is saved in an AVP from 'avplist'. If 'avplist' is missing, the
AVPs are named 1, 2, 3, ...

Meaning of the parameters is as follows:

command - Command to be executed. It can
include pseudo- variabes;

avplist - comma separated list with AVP
names to store the result in;

WARNING: if the var you are passing out has a bash special
character in it, the var needs to be placed inside quotes, for example:
exec_avp("print-contact.sh '$ct'");

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

Example 1.5. exec_avp usage

...
exec_avp("echo TEST");
exec_avp("echo TEST", "$avp(s:test)");
...

5. Known Issues

There is currently no guarantee that scripts ever return and stop
blocking the SIP server. (There is kill.c but it is not used along with
the current mechanisms based on popen. Besides that kill.c is ugly).